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Absolute OpenBSD, 2nd Edition by Michael W. Lucas

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File Flags

All Unix-like operating systems share a common permissions scheme, but OpenBSD (and most BSD-based operating systems) extends the permissions scheme with file flags. File flags work with permissions to change file security. Flags can make a file unchangeable, make it so that existing data cannot be removed and users can only add to the file, and produce several other effects. Some flags have functions unrelated to security, but we’ll pay special attention to the security flags. File flags are listed and documented in chflags(1).

File Flag Types

Many file flags have different effects depending on the system securelevel, which we’ll cover in the next section. Understanding how securelevels work requires an understanding of file ...

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